The present invention relates of a device for the treatment of benign prostatic hyperplasia (BPH), which is a benign proliferation of the prostate gland which can, and frequently does, lead to an obstruction or constriction of the urethra which extends through the prostate and thus to considerable impairment of urination and emptying of the bladder.
For the treatment of BPH, cold (cryosurgery, now abandoned) and heat, produced, for instance, by microwaves or ultrasonics have been used for a long time, in addition to surgical methods in order to obliterate the obstructing tissue.
In recent years, laser applications have been increasingly proposed in which the obstructing tissue is heated and denatured, or even directly vaporized, either in contact with the tissue or without contact by radiation with laser light. The laser application can be effected both from outside the tissue and from within the tissue (interstitial).
It is common to all these methods that the treatment devices are very large and expensive, both to purchase and to use. It has furthermore been attempted to destroy prostatic tissue by means of metal wires or metal plates arranged on the end of special instruments, which are introduced into the urethra and made red hot by electric current, which are in contact with the prostatic tissue. The considerable side effects due to poor control of the effects have, however, prevented this method from becoming a generally accepted method of operation. A survey of the present state of knowledge with regard to the effects of cold, heat and light on prostatic tissue, as well as the present state of medical technology can be noted from an article by R. Muschter and A. Hofstetter entitled "Thermische Therapie der benignen Prostata- hyperplasie" Thermal therapy of benign prostatic hyperplasia!, Munchener Medizinische Wochenschrift 134(40):630-634, 1992.
In an article by A. Roggan and G. Muller, "Computer simulations for the irradiation planning of LITT", MEDTECH 4(2):18-24, 1993, computer simulations which describe the action of lasers in the near infrared are indicated. Due to the great depth of penetration of these wavelengths, the large coagulation regions of diameters of 25 to 30 mm which have been experimentally described upon interstitial application have been verified and explained on the phantom.
The use of a pure heat source was considered insufficiently gradated as compared with this, since the effect of the heat conduction which is applied in this connection, due among other things to the cooling action of the blood flowing through the tissue, limits the necrosis
From Federal Republic of Germany 33 15 303, a method and a device are known for producing defined thermal damage to biological tissue in which, however, only a superficial coagulation is desired and not a depthwise action. In that known device, a heating element is provided by a coaxial construction consisting of a well-conducting center conductor and a tubular outside section consisting of a material having electrical resistance which forms a heating region. The tubular heating element is of relatively low resistance and is acted on by very short current pulses of high amplitude. Furthermore, said heating element has dimensions which do not permit insertion into the interior of tissue.
The heating tip can be fed both with alternating current, particularly an alternating current of higher frequency, and with direct current.
Due to the fact that the heating tip itself or the heating region is thermally insulated from the rest of the contact applicator, a targeted application of the heat can be obtained without neighboring regions of tissue being damaged.
In the device of the invention, electric current is used as source of heat for the interstitial thermal therapy, in which connection the side effects which occur with the previously known devices being dependably avoided in a simple manner.